Process for obtaining protein from oil seed residues



Patented Aug. 16, 1949 r ormce PROCESS FOR OBTAINING PROTEIN FROM on. SEED RESIDUES Glenn Davidson, Aurora, 111.

No Drawing. ApplicationApril 12,1945.

Serial No. 588,073

Claims. (01. 260-112 The commercial practice of extracting protein from oil seed residues, such as soy beans, has been characterized'by low yield of protein as comwith the total protein content of the raw material, and particularly difiicult and expensive sumption per unit of material treated. Where a large proportionjo'f the protein content thus fails of extraction, such procedure is unduly wasteful and expensive. ,In accordance with the present Other objects and advantages will appear from the following corn germ, etc., constitutes raw material which may be worked-up in accordance with the present invention.

For extracting isolated vegetable protein from material of this character heretofore, the operation has been commonly divided into five distinct steps as follows: a

1. Solution of the protein in aqueous alkali.

2. Clarification of this solution. c

3. Precipitation of the protein from this alkaline solution by reduction of the pH,'i. e., the addition of acid. 7

4. Dewatering of the precipitated curd to a reasonable moisture content.

' 5. Drying of the curd.

Due at least in 2 Dorrco (internal drum) type worthless for this reason alone. The'result is that up to the present, only high power consuming centrifuging has been employed. Even :with centrifuging, it is impossible to get a product sufficiently free of cell fragment material to permit spinning into filaments, i. :enprotein rayon, except at prohibitively slow rates'of flow, through the, centrifuge. The successful filtration of aqueous extractsof protein containing residues involves the formation of a filter bed of the water-swollen cellular material of the residue whilesimultaneously extracting the I protein therefrom, and auto-filtering' the protein extract through the cellular material from which it has been extracted. In its preferred form, the filter bed of water-swollen cellular material will minimize the segregation of the hemicellulosic gums and cell fragment material into a distinct layer of appreciable depth, capable of slowing the rate of flow. Also to be avoided is any wedging or excessive packing of the filter bedyresulting from the swelling of the cellular material during the formation of the bed. In order to form a successful filter bed, several precautions must be carefully observed. Foremost among these precautions are the mechanics of the formation of the bed, the selection of the protein containing residue for its mechanical condition and its non-protein con stituents and the selection of a proper aqueous protein solvent. V g

"If the oil seed residue, after removal of the oil, for instance in the form of solvent-extracted flakes'such as soy bean flakes (e. g. extractor flakes all passing a 4-mesh screen and containing 20 per cent passing a IO-mesh screen and 5 per cent an SO-mesh screen) is stirred into an aqueous alkaline solution in a' container provided with a controleld drainin the bottom and is allowed to settle, the heavy or fibrous particles settle or stratify at the bottom of the container and thereabove are progressively smaller particles, finally the hemicellulosic germs and cell fragment material, and at the top clear supernatant liquid. If 10 parts of alkaline solution to 1 part of residue is used, as is a. convenient proportion, although it may be varied considerably each way, the settled residue will occupy approximately the lower twothirds of the container. As alkaline solvent, about 5 parts of borax or trisodium phosphate per 'lbs. of dry' residue is very satisfactory, although this proportion may be decreased by several parts, or may be increased, up to 20 per cent based on weight of the flakes. Other alkaline agents which may be used'are alkali phosphates,

sulphites, etc. Carbonates are much less desirable, on account of the disturbance occasioned by the disengaged carbon dioxide gas in the stage of acidulating. Caustic alkalies, such as caustic soda or potash, and even ammonia, are undesirable at this stage, being too active in swelling and gelatinizing the gum; The alkali may be omitted entirely and the pr'ricedure used to make water extracts. With the material disseminated in the alkaline solution and the fibrous the bottom, as above referred to, the outlet of the container is now opened so as t6 snow to drain slowly and filter through the fibrous layer which is formed at the bottom; It will be understood that suitable fiber, or the like, on a grill, is provided slightly above the bottom of the container, to revent escape of the ing through the mass of residue is well clarified and contains a substantial portion of the protein ofthe original material, and this works suitably where the total depth does not exceed about three feet. For operation with greater depths of liquid, further modifications are desirabl l he reason for this is that (l') the particles of the residue become broken up somewhat by the mechanical stirring andresult in an increased percentage of fines, and 23 a considerable portion of the protein is dissolved during the initial stirring, and this tends to deflocculate or disperse the fine material and keep it. in suspension, and this i'orms an upper gummy layer above the lower fibrous or largest particles or the residue which tends to clog and low the filtration; Accordingly, it is preferred to carry on the separation in a cortainer whichis oi hopper shape or wider above than below, its wall converging to a narrow outlet end below. The dry residue may be charged into such container, and the aqueous alkaline solutionbe then run in at the bottom at a, rate not materially churning up the mass, and after the liquid is all run in, the valve is closed until ready for draining. With such upwardly expanding section of the container, the cellular material swells and expands laterally and upwardly, without wedging, as may occur in a container with vertical sides, and the fines are entrapped in the residue to such an extent as to essentially eliminate the top gummy layer. now opened, and the liquid is auto-filtered through the filter bed of water -swollen cellular material. A wash of further alkaline solution, or water, may be run in, if desired, and also be drained V Auto -filtration is commercially practicable only with protein residues of the solvent extracted flake type and not with meal made from expeller or hydraulic press cake. All of the reasons ior this are obscure but perhaps a description of the two types of material will be helpfu In the case of solvent extracted soy bean flakes, for example, the coarsely cracked beans are passed between very heavy duty rUlls prior to the removal of the oil by the solvent. Elaborate precautions are taken to have the beans at an optimum moisture content and temperature, to produce the largest possible flakes at a minimum thickness and a minimum amount of fines. Precautions are also taken to cause each bean particle to pass between the rolls individually so that each resulting flake is an individual entity and not compacted with another.

Typically the flakes coming from the flaking rolls may be 0.5" in diameter and ;010"-"0.-015" layer formed at support, as cloth, glass 4 The bottom valve. is u.-

the liquid fibrous material. The liquid filter-,

'75 fines into a gummy layer capable of retarding in thickness. As these flakes pass through the equipment for the removal of the oil by solvent, naturally they are broken up somewhat so that the largest flakes in the final solvent extracted product commonly are not more than 0.25" in diameter and average, perhaps, 0.125 in diameter. I

The oil contentof solvent extracted flakes is ordinarily about 0.75%.

On the contrary, in the expeller and hydraulic press processes for removing the oil, the individual been particles are compacted together into computatively massive units which require grinding before any protein extraction with aqueous s01- vents can be undertaken.

When expeller or hydraulic press cake is ground substantially equi-dimensional particles are obtained; Now, the 0.015" thickness of solvent extracted flakes probably represents about the maximum distance through which efiicient extraction of the protein can be obtained by the necessary diffusion processes. Accordingly, in order to get equal statistics; or, protein extraction from the individiial particles, the expeller or hydraulic press cake must be ground until the particles approximate 0.015 in diameter.

It is obvious that if two solv'e'nt extracted flakes, each 0.015" in thickness and 0.125" in diameter are placed facet'o-face, a continuous passageway 0.125" in length exists between them. Likewise it is obvious that if two equi-diinensional particles 0.015 in diameter, ground from expeller or hydraulic press case, are placed together, the length of the continuous passageway between is 0.015. Thus, it is seen that the average length of the continuous uimcuit y blockadabl'e passageways through a filter bed of solvent extracted flakes can easily be several times as great as through a filter bed or ground expeller or bytitaullc press cake.

The ejipeller and hydraulic press cakes contain 5.0 34.0% oil a d somewhat larger amounts of lecithin and lecithin like substances than the solvent extracted flakes. I Now soaps, which ma be formed by the interaction bf the alkaline protein eutraetant a'r'id the on, as well as the lecithin, are extremely good dispersing agents or deflo'cculators for the hemicellulos'ic gums and cell fragment material. Accordingly, the hemicellulosic and cell fragment material of "ground expeller or hydraulic press cake disintegrate into 'sliih'e' capable or blh'cki'n'g the filter bed to 'a much greater extent than is the case with solvent extracted flakes.

instead of initially stirring the residue intothe alkaline solution or running the alkaline solution filth the charge of dry material, a particularly desirable procedure is to charge the aqueous alkaline solution into the tank, of either form described, and then sprinkle the dry residue over the top or the solution at a rate not faster than it will wet out, sink into the liquid and settle. After the residue is all in and well settled, the outlet in the bottom of the, tank is opened as described above, and the liquid is auto-filtered through the filter bed of water-swollen cellular material.

Inall cases the treatment with the aqueous alkaline solution is thus on a prompt schedule which, without much agitation, provides for dis-- solving protein and simultaneously forming a fitter bed of water-swollen cellular material and avoiding the production and the segregation of protein in the filter residue.

flow, and the liquid being auto-filtered through such bed of cellular material. j

With the effective extraction of protein thus attained, however, the filtrate or obtained solution containing dissolved protein as coming through the filterfbed, still leaves considerable This. is accordingly further treated as described below, but the filtrate which has been obtained is acidulated'toa pI-I to eifect precipitation, viz. about 4.5, andthe'protein is thrown out as a curd. This is washed and is dried.

The filter residue above referred to is now subjected to treatment with another aqueous alkaline solution or is digested, 'with'dilute' caustic soda solution or other alkali, as, for example, 0.4 per cent, or 4 per cent NaOI-I calculated on the dry residue basis. The concentration of this extracting solution may be varied somewhat above or below this amount. The mixture of liquid and suspended residue is then passed over a fine perforated surface, such as a ZOO-mesh (or finer) screen. Preferably, this screen is set on an incline of between 5 and 40 (preferably between 15 and 30) to the horizontal, and the material is fed so as to flow down the slope of the screen, being distributed bysuitable means, as a pipe or trough with a series of perforations, or a dam with notches, or by a spray, etc., and the I screen should be vibrated in its own plane and at right angles to the direction of flow of the material. The amplitude of vibration may be about A," to A1", and a satisfactory frequency is 500 per minute, but this may be varied-somewhat higher or lower.

subjected to sufiicient vibration and supply of liquid to wash the very fine particles of hemi- A zone of separation is correspondingly provided, in which the suspension is cellulose through the perforations, while-the fibrous material or cellulose is screen. The liquid obtained is a solution of further extracted'protein and with very fine suspended gelatinized gum or hemicellulose particles. On now acidulating to a pH of approximately 4.5, the dissolved protein and the hemicellulose are precipitated out together. This precipitate is washed and is dried.

The protein yield from the ,first stage treatment with the alkaline solution is about lbs. per hundred pounds" of the original residue treated. The solids obtained on the first separation amount toaround lbs. per hundred of the original material, this containing about 40 per cent protein. With the further digestion with alkaline solution as described an additional yield of about 32 lbs. per hundred of the original'inaterial is obtained, this being made up ''ofprotein intimately mixed with 40-50 per cent of hemicellulose. The first fraction of protein obtained is suitable for any fine usage, nutritional or industrial. The second precipitate of mixed protein and hemicellulose is particularly well suited for certain paper coating or adhesive usages. The final solid residue from the separation of the last solution is predominantly cellulose fiber, with screened-out particles of hemicellulose or gum, and some residual protein, and is suitable for stock feed mixtures.

The acid used in both precipitations may be any suitable mineral acid or acetic acid, usually sulphuric acid, and in concentration about 6.0 per cent H2504.

Other modes of applying the principle of the invention may be employed, change being made as regards the detail described, provided the rejected by the swellfi'n azone divergently widening above while he {fibrous component stratifies convergently below; filtering 'th'e'solution through the fibrous stratum, digesting the filter solids in an aqueous caustic alkali solution, passing the resultant dispersion to a separating done and permitting escape-of liquid but rejecting particles of fiber liile'agitating and differentially washing smaller l'iemiceilul0se particles through with the liquid, and acidulating the liquid and precipitating protein and hemicellulose together.

- 2.";In a process of working up oil seed residue, sprinkling solvent-extracted flake oil seed flake residue particles on an aqueous alkaline salt solutionat rate not faster than they wet and sink in the liquid, and dissolving the protein and swelling the gummy component of the material and stratifying the fibrous portion below, filtering the solution through the fibrous stratum, digesting the filter solids in an aqueous caustic alkali.

solution, passing the resultant dispersion to 'a separating zone and permitting escape of liquid but rejecting particles offiber while agitating and diiierentiallywashing smaller hemicellulose particles through with the liquid, and acidulating the liquid and precipitating protein and hemicellulose together. I I

' 3; In aprocess of working up oil seed residue, incorporating the flake oil seed flake residue particles with an aqueous alkaline salt solution, allowing the gummy component of the residue to swell and the fibrous component to stratify below, filteringthe solution through the fibrous stratum, digesting the filter solids in an aqueous caustic alkali solution, passing the resultant dispersion to a separating zone andpermitting escape of liquid but rejecting particles of fiber while agitating-and differentially washing smaller hemicellulose particles through with the liquid, and

acidulating the liquid and precipitating protein,

and hemicellulose together.

4. In a process of working up oil seed residue, sprinkling the flake oil seed flake residue parti-cles on an aqueous non-acid protein solvent at a rate not faster than they wet and sink in the liquid, and dissolving the protein and swelling ":the gummy component of the material in azone divergently widening above while stratifying the fibrous portion convergently below, filtering the solution through the converged fibrous stratum, digesting the filter solids in an aqueous caustic alkali solution, passing the resultant dispersion to a separating zone and permitting escape of liquid but rejecting particles of fiber while agitating and differentially washing smaller hemicellulose particles through with the liquid, and acidulating the liquid and precipitating protein and hemicellulose together.

5. In a process of obtaining protein from oil seed residue, charging solvent-extracted flake oil seed flake residue into a zone divergently wider above, introducing an aqueous non-acid protein solvent up through the bottom of the material without substantial disturbance thereof, and dissolving protein therefrom and by such solvent swelling the gummy component of the material and stratifying the fibrous portion convergently eeedxe s ri k in th fi ek e ks e a .0 I

resid Pa t l n ne ueeusn aeci P ote n s e t e nbw t tna th y w e s nk; i t i an ol inethe Pr tei a d :bysue s e w l m h L umrI ycomponent o th m t me n d veree t -,wid ie v1 e ln prn l l oli ti -r l h ioee nb i e e ee ge lfilt ne, be -s tu-lb ve r i' e t fibrou ie o ver en' lylom an -;f t he sel t n thr e th -convene ;.fibr u s um filtee ebe In a pr c s ed; w ee rrree e s rinkl n th fla n edfiek .re ie ert e e en a a ue -a id Pr ei solven fi m m te ith nt v e an sink in the liquid, and. dissolyingthe protein and .le l eelven ewellin lt :mmmwemmee 118 e eari ia l rie be iin th qfibnoe porti pn. be wleni 1 21. fibmu stratum V n az p qe s in lqbtaimn Pr ei immyo re idue m xin se ven eetraete ak x9 e at .reele wit e e ue e neplsetei .eelv len e liseq v n lth e-PliQ fim an r e er n ef r nete ims 's t ine the -,js lved pe till J2IQQ$-9IQPQQ1Y tt vb e su e si mles meeet y t e ie4-b e lln mater nveflelnel ne z-r es eet m en pm ve w de in the fibrous filtering bed.

mabov reed new: filter n th olu n rou h as B in al;.proqess of istamine protein, from, oil

ssee rr f ldue e'. .e tin in a ew u o ..eei tei eel e eo venteextra te r k oi n e la esid eiearti les ntai in .notlov nen ent whi e r as ii lmee ia idbii su hs lre eeetivel eswe inestheguxnlmy-mrtie eimsu e ei o -ee l i se inet eip etei an reparin 5e hie-b i -e t -stra i xi eath fib q a. p t f q e w en nel-v l e n jtheso v t lrmle .S ezf te lnel 7 A9 1 pr e ,0 1- bteieinei-l z e 1 rom-ni lse ee i e mixin h I la residu -e queq elkallmeal eqlutieneswel neith ummy component therein dissolving protein prepaning a filteiqingg bed in; situ V. by stratifying a th br i or io -i eanrq e s ve y n r ow ng- ;ezqn e W relrd gfin ly fil er n t v oluti n xthrong-h the {progressively gnarrowin afibrous ezone 11.I;n a proces s pf obtainingproteinfrom oils.

.seed i, residue, spninlsl-ing solvent-extracted oil e$ ufl ls n i ffie lleq lsolution v41f horax,

o ai in rote i nq eo r1 5 ;-,pe2e1:f .ne@

oil seed material to se e l lt e ro ein iiee etien .iriat r a (were.

13. In a pro lseedi-ee i l e S linthe hora; s, ution prepar ng a filter in situby ed lees;

l zifilt rle e i nar it i b .e wineth ttle, .and. draining the. re-

thmla th s t eifi te ie bedin,si by allowing the ,g nate almto settle, and draining the reinlgling solventrextracted the settled oess of obtaining protein from oil- 7 e n an. aqueoys solution pf-borax v iret u le f ee ltha i i W d sink allot 'nethe residuto sink-and forma filter bed,

aq iegnis bogax ;th ;ough lsuch filter bed,

20 e i x let e.

eth peetei h l-resliltm u io o P te i g the res iltant filtrate toprecipitate efro m.

P e b ebte ein i e e m flake 2 -;filtpr ibed, draining the resulting ,solution, of through such filter bed, ltant: filtrate to precipieeiet met-e the e ro pre e eii reeueeu borex, acid 1 ting the :resu

and

t -eein i-en la lee ne zsqlut l ifi te i ealee t 'Pmci ta 1 1. I a v a ee -resi u f see 3 3 Re i 9 i a met ,z z t te 5t e riw :-75sa s t r li ie teet leme teeter-re d ;n r le e con ainin v .2

' ee -40 i nesh, onsan aqueousalkaiine of protein through M pr ein thei efrqm. pr ces -:9 einine r e om then eed;;residue, preparing a- ?41 n zthe' e id t Sink and 0 per such leti ie t e re lt fi a flake l ng;solvent extraeted oilaqi eous ;solu.ti on of borax at towet and lsinla in the bli io a n n borax t;up ,to; 20;per, cent of; the d y filter form GLENN DAVIDSON.

.1REEERENQE5S. CITED Number s LUNETE 5 A E AT N Bonotto Feb. 27,

Certificate of Correction Patent No. 2,479,040 August 16, 1949 GLENN DAVIDSON It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 6, line 14, for the Word done read zone; lines 21, 37, 51, 69, and column 7, lines 5, 16, 27, and 39, after seed strike out flake;

and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case 111 the Patent Ofiice.

Signed and sealed this 27th day of December, A. D. 1949.

THOMAS F. MURPHY,

Assistant Oommissz'oner of Patents. 

